You can also check the "date modified" and save games are numbered from 0000 to xxxx anyway so the last/latest ones are usually the ones with the highest number.
I have a SSD so I like to keep it clean as well. I just backed up my save games folder to my internal backup HD and manually deleted ~2.7GB of save games, only keeping the most recent five. That was a matter of 30 seconds (if that) so it's not really a problem .